Steam turbines have to date been the most traditional way to covert heat into electricity. Steam turbines are able to convert between 35-60% of the heat into electricity. However, scientists have kept investigating alternative ways to turn heat into electricity. Thermophotovoltaic cells (TPV) were initially promising, but only ever achieved efficiency rates of 20-32%. By increasing both the temperature of the heat emitter & the absorption properties of the TVC (visible, ultraviolet & infrared) engineers at MIT have achieved efficiency rates of 40%, with a clear idea of how to reach 50%.
Under development since 2017, this liquid metal battery (LMB) is about to be let loose on the globe. Consisting of 3 liquid layers; 2 of molten metals and a middle layer of molten salts. The system is self-heating and insulated, but contains no combustible materials - so they can't burn. And they retain all of their charge capacity for at least 5000 cycles (think decades, not years). Modular, safer and cheaper than lithium-ion batteries. https://ambri.com/technology/